Developing Comprehensive Management Models for Marine Mammals

Submitted by donahue on 18 October 2012 - 11:47am

Principal Investigator(s):

Leah Gerber

Marine mammals are increasingly threatened by interactions with fishing gear, ocean noise, pollution, direct harvest, ship traffic, competition for food with fisheries, and coastal development. Managers must set limits to these sources of human-caused mortality and disturbance to marine mammals without compromising human welfare. Currently, the U.S. Marine Mammal Protection Act limits the allowable number of deaths caused by fisheries with a simple model called Potential Biological Removal. NOAA has also recently committed to developing mapping tools to better understand where underwater noise overlaps with the distribution and density of cetaceans.

Although these two approaches are a vast improvement to the status quo, there are still major limitations: 1) they do not consider the cumulative impacts of all threats, and 2) they assume largely unrealistic population dynamics. We propose to develop a new framework for setting removal limits that incorporates cumulative impacts, and also allows for more realistic population dynamics, especially with respect to social complexity in marine mammals. Our analyzes will provide managers with clear guidelines for managing the threats that marine mammals encounter in space and time.

UPDATE: October 2013

NCEAS support allowed our working group to develop the first comprehensive database of social behavioral, ecological, and demographic data for marine mammals. Once complete, we plan to use these data to examine the relationship between population dynamics and sociality (defined here as the broad system of conspecific attachment, association, knowledge, communication, culture and behavior in group-living species). In addition, we are developing a quantitative index of sociality, an innovative method of estimating phylogenetically-corrected demographic and life history parameters, and species-specific demographic rate estimates essential for conservation and management.

We have also successfully developed and implemented an expert opinion survey to assess cumulative impacts of multiple stressors on marine mammals and are developing a framework to integrate the elicited expert knowledge with empirical data for input into a population model. Our work with NOAA Southwest Fisheries Science Center will aid in the conservation of these culturally significant marine species by providing better-informed forecasting models to decision-makers. Further, the methods we are developing will provide detailed estimates of demographic parameters crucial for the study and management of rare and data-deficient species.

This work is supported by the National Center for Ecological Analysis and Synthesis, a Center funded by NSF (Grant #EF-0553768), the University of California, Santa Barbara, and the State of California.